1. Field of the Invention
The present invention relates to a rotary actuator for a motor vehicle, having a control knob, a housing, an actuating shaft that is rotationally fixed to the control knob, and electromagnetic means that acts on the control knob so as to permit a detent or locking of the rotation of the control knob.
2. Description of the Background Art
Oftentimes in modern motor vehicles, operating elements are used that have multiple control functions assigned to them. Thus, through selection in a display or menu buttons a rotary actuator can be given the control task of adjusting the volume of a radio receiver and can at the same time be given the control task of adjusting a three-speed fan. In this connection, different types of tactile feedback as well as limits as end stops have to be implemented in one rotary actuator.
One possibility for achieving different detent positions in a rotary actuator is described in DE 101 53 002A1. The rotary actuator includes an actuating shaft that is rotatably mounted in a housing with a detent arrangement that cooperates therewith and contains a rotatable holding element, which can be braked or locked with respect to the housing by an associated solenoid-controlled locking element in order to activate the detent arrangement, wherein the solenoid contains a magnetic circuit consisting of a hole and a movable armature arrangement, and also contains a winding. In this connection, the magnetic circuit contains a permanent magnet that is designed and arranged such that the solenoid acts as a bistable solenoid that may be switched through brief application of current to the winding. The arrangement of teeth and a detent ring that surrounds the teeth and works together with the solenoid permits individual adjustment of the detent action. Also described is the use of locking elements similar to brake calipers, which act on the surface of a detent element that is at least disk-shaped or arc-shaped, in order to produce suitable tactile feedback.